I beleive it is A off of a zero kill chain, as your kill chain goes up the chances of receiving the item goes up also.

Just a quick suggestion, if at all possible move 2 screens away. This will cause all bad guys in the zone you want to fight into to respawn at once.

255 Necros will cause LE
Never heard about this, doubt it works that way. Woudn't waste my time trying either.